I have a 2001 A4 1.8t. There is a slight grinding noise coming somewhere along the serpentine belts route at the front of the engine. I took it to bell tire and the mechanic suggested that it was the belt tensioner, so I replaced that but the noise still persists. I can't pinpoint it, but it seems like it may be coming from the fan clutch, the alternator, or the other pulley down below (not sure what that drives.......a pump of some sort?)

Also the noise seems to correlate to engine RPM: it will get faster and eventually be unnoticable about 3500 RPM. When it's idling though it's very noticable but doesn't cause a rough idle or anything. I don't know whether or not the serpentine belt correlates to engine speed, so I could be completely wrong about the noise coming from somewhere along the serpentines pulleys.

Has anyone else experienced anything like this or know where the problem might be? That area is a pain to get to, so I would like to be reasonably positive about what's making the noise before putting in the work to change the culprit part.

 

Buy a $10 stethoscope & listen to each rotating component. You will hear a growling noise from the bad apple.

 

Unfortunately getting anywhere close with a stethescope is nearly impossible given the limited space, at least I'm not willing to risk fingers for it

Further investigation revealed that the other accessory is the power steering. So my two suspects at the moment are that and the alternator. And the noise is now very pronounced now; sounds like a hollow scraping and grinding....can't really think of anything to compare it to. I am wondering if either of these units could be making this noise without the obvious side effects of them being broken completely (no battery charge and no power steering)

The radiator fan is still suspect as well.

Has anyone had any experience with either the fan, alternator, or power steering units going bad and making these noises? And is it possible that just the pulleys attached to these could be bad and be replaced?

Thanks

 

Use a long stethoscope!
Do not put fingers near rotating objects!